FLOW VISUALIZATIONS DURING TOP VENTING FROM A SMALL VESSEL

To study the venting characteristics of foams and high-viscosity fluids, a 13 litre glass facility was built. The fluids used were pure water, foamy water and fluids with viscosities of 0.013 and 0.19 Pa s (giving values 73 and 1061 times that of water at 150-degrees-C). The resulting blowdowns show that differences in venting characteristics (pressure history and vented mass) are due to differences in the flow regimes. The low viscosity fluids have a churn-turbulent flow pattern, while the high viscosity fluid forms a 'two-phase emulsion' through which large bubbles rise. The experimental results are compared with existing data. Good agreement between the two sets of water and foam data is demonstrated but there is a discrepancy between the two sets of high viscosity data.